linux-kernel - [PATCH] misc: eeprom: at24: Always append device id even if label property is set.

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Message-Id: <20210701152825.265729-1-jglisse@redhat.com>
Date:   Thu,  1 Jul 2021 08:28:25 -0700
From:   jglisse@...hat.com
To:     linux-kernel@...r.kernel.org
Cc:     Jérôme Glisse <jglisse@...hat.com>,
        Diego Santa Cruz <Diego.SantaCruz@...netix.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Jon Hunter <jonathanh@...dia.com>, stable@...r.kernel.org,
        linux-i2c@...r.kernel.org
Subject: [PATCH] misc: eeprom: at24: Always append device id even if label property is set.

From: Jérôme Glisse <jglisse@...hat.com>

We need to append device id even if eeprom have a label property set as some
platform can have multiple eeproms with same label and we can not register
each of those with same label. Failing to register those eeproms trigger
cascade failures on such platform (system is no longer working).

This fix regression on such platform introduced with 4e302c3b568e

Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
Cc: Diego Santa Cruz <Diego.SantaCruz@...netix.com>
Cc: Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc: Jon Hunter <jonathanh@...dia.com>
Cc: stable@...r.kernel.org
Cc: linux-i2c@...r.kernel.org
---
 drivers/misc/eeprom/at24.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 7a6f01ace78a..305ffad131a2 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -714,23 +714,20 @@ static int at24_probe(struct i2c_client *client)
 	}
 
 	/*
-	 * If the 'label' property is not present for the AT24 EEPROM,
-	 * then nvmem_config.id is initialised to NVMEM_DEVID_AUTO,
-	 * and this will append the 'devid' to the name of the NVMEM
-	 * device. This is purely legacy and the AT24 driver has always
-	 * defaulted to this. However, if the 'label' property is
-	 * present then this means that the name is specified by the
-	 * firmware and this name should be used verbatim and so it is
-	 * not necessary to append the 'devid'.
+	 * We initialize nvmem_config.id to NVMEM_DEVID_AUTO even if the
+	 * label property is set as some platform can have multiple eeproms
+	 * with same label and we can not register each of those with same
+	 * label. Failing to register those eeproms trigger cascade failure
+	 * on such platform.
 	 */
+	nvmem_config.id = NVMEM_DEVID_AUTO;
+
 	if (device_property_present(dev, "label")) {
-		nvmem_config.id = NVMEM_DEVID_NONE;
 		err = device_property_read_string(dev, "label",
 						  &nvmem_config.name);
 		if (err)
 			return err;
 	} else {
-		nvmem_config.id = NVMEM_DEVID_AUTO;
 		nvmem_config.name = dev_name(dev);
 	}
 
-- 
2.31.1